A promising technique of producing nanostructures, i.e. structures in the order of 100 nm and smaller, is so-called nanoimprint lithography, however this technique may also be used to microstructures. This technique is described in the document U.S. Pat. No. 5,772,905, which is incorporated herewith by reference. In such lithography, the main steps of which are schematically shown in FIGS. 1a-d, a pattern of nanostructures is transferred from a stamp 1 to an object 2. The object 2 consists of a substrate 2a and, applied thereto, a film 2b of a polymer material (resist). After heating of the film 2b to a suitable temperature, the stamp 1 is pressed into the same (FIG. 1b). The stamp 1 is then released from the object 2 when recesses 3 of a desired depth have been formed in the layer 2b (FIG. 1c). Subsequently any remaining film in the recesses 3 is removed, for instance by etching, thereby exposing the substrate or in some other material which is applied to the substrate.
A device according to the above mentioned US patent for carrying out the above lithographic process comprises a first contacting means with receiving surface for the stamp, a second contacting means for contacting or joining the first and second receiving surfaces with each other.
The film applied to the substrate is very thin, typically 50-200 nm. For even structuring of the object, the stamp and the object must thus be mutually parallel with an accuracy of a few nanometres.
Especially due to the fact that the high requirements in accuracy, when manufacturing micro and nanostructures, in the alignment between the stamp and the object, there is a great need for exact control of the movement of the stamp in the direction perpendicular to the pressing direction, as a small displacement of the stamp can have the severe consequence that the pattern transferred to the object cannot be used.
The substrate is usually made of a brittle material, e.g. Si/SiO2, GaAs or InP, and the pressure exerted upon the substrate during contact is high, typically 4-10 MPa.
In the case where a pattern is to be transferred to both surfaces of the object in a single process, there is established a need for a still more reliable controlling of the stamp in the direction perpendicular to the pressing direction. Particularly in this instance it is important that the transferring of the patterns has a high accuracy as the matter could be that the object is totally destroyed and thereby not usable.
Furthermore to obtain that the pattern is transferred to the object in expedient manner, the object is heated to a temperature approximately between 150 and 300° C. This high temperature of the object during pressing causes that heat is transferred from the object to the surroundings, i.e. the stamp as well as the contacting means. During this heat transmission an uneven temperature distribution (also during subsequent cooling of the object) in the known devices is obtained, whereby changes in the shapes and sizes of the contacting means as well as stamps occur and thereby displacements of the elements in the devices may arise. This will have a severe consequence for the final product, due to the fact that only a minimal displacement of the pattern in relation to the intended placement will render the product useless.